As a system for storing large-scale data from a host, a storage apparatus which controls data I/Os from the host is used. The storage apparatus is an apparatus for managing, in a RAID (Redundant Array of Independent Inexpensive Disks), a multiplicity of drives arranged as an array. At least one or more logical areas (hereinafter these areas may also be described as logical volumes) are formed in physical storage areas which are provided by the multiplicity of drives installed in the storage apparatus and the logical volumes are provided to the host.
In order to store large-scale data from a host, a storage apparatus holds a large capacity storage area, but data from hosts has gradually increased over the years and there is a need for efficient storage of large-scale data due to problems relating to the size and cost of a storage apparatus.
Therefore, a reversible data compression system, which makes it possible to reduce the amount of data and replace same with other small-size data while maintaining the amount of information of substantial quality in the data, has been applied to a storage apparatus.
For example, PTL1 discloses a storage system with which data is compressed and the optimum storage position is selected on the basis of the compressed data size.